Coating the crude gas tract of a fly-stream gasification plant with a heat-resistant anti-stick layer

ABSTRACT

A fly-stream gasification device for a process that employs powdery or liquid fuels—where liquid fuels are to be understood as oils, or oils containing solids, and water or oil suspensions containing fuels ground to the consistency of dust or inorganic additives—at pressures of between ambient pressure and 8 MPa and gasification temperatures of between 1,200 and 1,900° C., and which has a gasification means containing free oxygen, comprising a gasification chamber, a quenching device, and an element that belongs to the crude gas tract and ducts the crude gas, is embodied in such a way that an element ducting crude gas is made of heat-resistant carbon steel and furnished on surfaces in contact with the crude gas with an anti-stick layer able to withstand a temperature of 250° C. for preventing the carbonates that form from sticking.

CROSS REFERENCE TO RELATED APPLICATIONS

This application claims the benefits of German application No. 10 2007 037 860.4 filed Aug. 10, 2007 and is incorporated by reference herein in its entirety.

FIELD OF INVENTION

The present application relates to a fly-stream gasification device for a process that employs powdery or liquid fuels—where liquid fuels are to be understood as oils, or oils containing solids, and water or oil suspensions containing fuels ground to the consistency of dust or inorganic additives—at pressures of between ambient pressure and 8 MPa and gasification temperatures of between 1,200 and 1,900° C., and which has a gasification means containing free oxygen, having the features of the preamble of claim 1.

BACKGROUND OF THE INVENTION

During the gasification process with full quenching at working pressures of up to 8 MPa (80 bar) the hot crude gas streaming saturated with water vapor from the reactor/quencher (1) is subjected at a further process stage to gas purification through water washing. Carbonate precipitations form on the pipeline wall and washers in the connecting pipeline (2) from the quencher to the washers (3, 5), in the washers themselves, and in the pipeline (4) from the first to the second washer. The carbonate formation is due to the occurrence of alkali metals in the ash of the material being gasified (coal, slurry, or biomass) and hence to their presence in the crude gas as well as to the carbon dioxide as a crude gas constituent.

Particularly in the washers (3, 5), and therein especially when a Venturi washer is used, the precipitations cause narrowing of the Venturi throat's cross-section, which effect, owing to the consequent increased loss of pressure, reduces the plant's performance to the point where the gasification process has to be halted for cleaning.

The chemical process of carbonate formation will be lessened or, if a suitably acidic mode of operation is used, prevented through operating the quenching process at a pH value of <6.5. However, the consequence of employing the acidic mode is that the preferred use of economical heat-resistant carbon steels is not possible owing to the acid corrosion occurring with high rates of material removal. Acid-resistant and hence expensive materials have to be used instead.

SUMMARY OF INVENTION

The object underlying the invention is to embody a fly-stream gasification device in such a way that the quenching process can be operated at a pH value of >6.5 without the downtimes for cleaning for which provision customarily has to be made.

Said object is achieved in the case of a subject matter outlined by the features of the claims.

According to the invention, the washers (3, 5), specifically the Venturi tube, and the connecting pipelines (2, 4) are coated with a temperature-resistant anti-stick layer. Chemical nickel, chemical nickel PTFE, coating with a fluoropolymer, and special enamel may be cited by way of example. The coating prevents the carbonates that form from sticking.

Preventing precipitations by means of the surface coating furnishes the prerequisite for being able to operate the quenching process at a pH value of >6.5. That in turn offers the advantage that economical heat-resistant carbon steels can be used as the material for producing the washers (3, 5) and pipelines (2, 4).

Advantageous developments of the subject matter of the application are set forth in the dependent claims.

BRIEF DESCRIPTION OF THE DRAWINGS

The invention is explained in more detail below to an extent necessary for understanding by way of an exemplary embodiment and with reference to a figure, in which:

FIG. 1 shows a gasification device with fill quenching.

DETAILED DESCRIPTION OF INVENTION

Fuel and oxygen/vapor are ducted to a fly-stream gasification reactor at the top where the fuel is partially oxidized in a flame reaction at pressures between ambient pressure and high pressures of 80 bar (8 MPa) and at temperatures of between 1,200 and 1,900° C. Powdery or liquid fuels can be used as the fuel, with liquid fuels to be understood as oils, or oils containing solids, and water or oil suspensions containing fuels ground to the consistency of dust or inorganic additives.

The hot gasification gas exits the gasification chamber together with the liquid slag, then via the crude gas and slag exit enters the quench chamber into which water for cooling the crude gas and slag is jetted via quench nozzles. The slag is deposited at the bottom of the water bath and ducted away via a slag extractor. The quenched crude gas exits the quench chamber saturated with water vapor and at a temperature of 200° C. via the pipeline 2.

The crude gas is passed on via the crude gas tract that is formed by means of various elements such as, for instance, the pipeline 2 from the quencher to the washer 3, the pipeline 4 from the washer 3 to the washer 5, the washer 5 itself, and, if a Venturi washer is used, the Venturi throat. According to the invention, at least one element ducting crude gas, several or all crude gas elements ducting crude gas is/are made substantially of heat-resistant carbon steel as the material and furnished on surfaces in contact with the crude gas with an anti-stick layer able to withstand a temperature of 250° C. for preventing the carbonates that form from sticking. 

1.-8. (canceled)
 9. A fly-stream gasification device for use with powder or liquid fuels at pressures between ambient pressure and 8 MPa and gasification temperatures of between 1,200 and 1,900° C., and has a free oxygen gasification, comprising: a gasification chamber; a quenching device; and an element ducting the crude gas that belongs to a crude gas tract, wherein the quenching process operates at a pH value of >6.5 and the element ducting crude gas is made substantially of heat-resistant carbon steel and furnished on surfaces in contact with the crude gas with an anti-stick layer capable of withstanding a temperature of 250° C. for preventing the carbonates that form from sticking.
 10. The fly-stream gasification device as claimed in claim 9, wherein liquid fuels are selected from the group consisting of: oils, oils containing solids, water suspensions containing fuels ground to the consistency of dust or inorganic additives and oil suspensions containing fuels ground to the consistency of dust or inorganic additives.
 11. The fly-stream gasification device as claimed in claim 9, wherein the element ducting the crude gas is a pipeline.
 12. The fly-stream gasification device as claimed in claim 9, wherein the element ducting the crude gas is a washer.
 13. The fly-stream gasification device as claimed in claim 9, wherein the element ducting the crude gas is a Venturi tube.
 14. The fly-stream gasification device as claimed in claim 13, wherein the anti-stick layer is chemical nickel.
 15. The fly-stream gasification device as claimed in claim 13, wherein the anti-stick layer is chemical nickel PTFE.
 16. The fly-stream gasification device as claimed in claim 13, wherein the anti-stick layer is a fluoropolymer coating.
 17. The fly-stream gasification device as claimed in claim 13, wherein the anti-stick layer is an enamel. 